Muscle tissue structural changes and texture development in sea bream, Sparus aurata L., during post-mortem storage

Sea bream, Sparus aurata L., specimens were studied in pre-rigor (3 h) and during the following post-mortem days: 1, 5, 10, 15 and 22. Muscle and textural parameters were evaluated on 6 specimens/stage. Structural results showed scarce fibre-to-fibre detachment on pre-rigor, which increased during the post-mortem degradation. Ultrastructural changes revealed rapid muscle degradation. In pre-rigor myofibrils were detached to both sarcolemma and endomysium. Intermyofibrillar spaces increased and some mitochondriae and sarcoplasmic reticulum were swollen. After 1 day, the sarcolemma appeared occasionally disrupted and the interfibrillar spaces increased. From 5 to 10 days, the I-band and Z line presented some alterations, although these were more severe at 15-22 days. Thus, in these two last stages, loss of I-band, Z line and actin filaments was observed, that coincides with the alteration of the hexagonal arrangement in these advanced stages. Also, the fragmentation of myofibrils increased from 5 to 10 days on. Sarcolemma and endomysium were gradually disrupted throughout the post-mortem stages with total loss at 22 days. Consequently, the interfibrillar spaces increased at last stages. Autophagic mechanisms increased from 5 days on, with an intense destruction of all the intracytoplasmic organelles. Textural parameters decreased from pre-rigor until 5-10 days, mainly associated to detachment of myofibers to sarcolemma-endomysium.     

Electrodeposited composite coating of Ni-W-P with nano-sized rod- and spherical-shaped SiC particles

In this research, Ni-W-P-SiC nanocomposite coatings are electrodeposited from the plating solution containing suspension of nano-sized spherical- and rod-shaped SiC particles. The influence of SiC particle charge, applied current density, surfactant addition and the particle shape on the SiC incorporation rate has been studied. The phase structure, microhardness and wear resistance of Ni-W-P-SiC nanocomposite coatings were evaluated using X-ray diffraction (XRD), microhardness tester and wear test apparatus. The surface morphology of the produced coatings and worn surfaces has been investigated using scanning electron microscope (SEM). Additionally, the composite coating exhibited higher hardness and wear resistance than the pure Ni-W-P alloy. Regardless the particle shape, the mechanical characteristics of composite coatings are improved with increasing of SiC wt.% into the matrix. The corrosion behavior of the produced coatings was studied using anodic polarization measurements. The nanocomposite coating incorporating SiC rods exhibited higher mechanical and corrosion performance compared with deposits with spherical SiC nano-particles.     

Parameter determination for a generalized fuzzy model

This paper underlines a way to evolve a generalized fuzzy model (GFM), using the interpolation of CRI and TS models in their consequent parts of fuzzy rules. The GFM possesses the index of fuzziness of CRI model and the local model of the TS model. The parameters of the GFM are estimated by a two-step process. The consequent part of fuzzy rules is reformulated to suit the LSE framework for estimating the associated parameters. By assuming Generalized Gaussian membership function for the premise parts, Gradient descent technique is used to update its parameters. The performance of two classes of GFM has been tested on two systems and it is shown that class II GFM is the best out of all the fuzzy models tested.     

Scalable and fault‐tolerant key agreement protocol for dynamic groups

With the widespread use of the Internet, the popularity of group communication‐based applications has grown considerably. Since most communications over the Internet involve the traversal of insecure networks, basic security services are necessary for these collaborative applications. These security services can be facilitated if the authorized group members share a common secret. In such distributed applications, key agreement protocols are preferred to key distribution protocols. In the past two decades, there have been many proposals for key agreement protocols. Most of these protocols are not efficient and limit the size of the underlying group. In this paper, we consider the scalability problem in group key agreement protocols. We propose a novel framework based on extension of the Diffie–Hellman key exchange protocol. The efficiency of our protocol comes from the clustering of the group members, where the common session key is established collaboratively by all participants. We present the auxiliary protocols needed when the membership changes. We show that our protocol is superior in complexity in both communication and computation overheads required to generate the session key. Copyright © 2006 John Wiley & Sons, Ltd.     

Field-programmable smart-pixel arrays: design, VLSI implementation, and applications

A smart-pixel array is a two-dimensional array of optoelectronic devices that combine optical inputs and outputs with electronic processing circuitry. A field-programmable smart-pixel array (FP-SPA) is a smart-pixel array capable of having its electronic functionality dynamically programmed in the field. Such devices could be used in a diverse range of applications, including optical switching, optical digital signal processing, and optical image processing. We describe the design, VLSI implementation, and applications of a first-generation FP-SPA implemented with the 0.8-microm complementary metal-oxide semiconductor-self-electro-optic effect device technology made available through the Lucent Technologies-Advanced Research Projects Agency Cooperative (Lucent/ARPA/COOP) program. We report spice simulations and experimental results of two sample applications: In the first application, we configure this FP-SPA as an array of free-space optical binary switches that can be used in optical multistage networks. In the second, we configure the device as an optoelectronic transceiver for a dynamically reconfigurable free-space intelligent optical backplane called the hyperplane. We also describe the testing setup and the electrical and the optical tests that demonstrate the correct functionality of the fabricated device. Such devices have the potential to reduce significantly the need for custom design and fabrication of application-specific optoelectronic devices in the same manner that field-programmable gate arrays have largely eliminated the need for custom design and fabrication of application-specific gate arrays, except in the most demanding applications.     

Synthesis and sintering of cordierite sol-gel powders based on different magnesium salts

The effect of the nature of the magnesium salt on synthesis and sintering of cordierite powders made by the sol-gel method was established. The phase composition of the powder and behavior of the material in sintering are a function of the calcination temperature of the xerogels.     

The idealized structural unit method and its application to deep girder structures

An efficient method of analysis of non-linear behavior until collapse of large size redundant structures is presented. The method is named as The “Idealized Structural Unit Method”. In this method the structure is divided into the biggest possible “Structural Units” whose geometric and material nonlinear behavior can be idealized and described in a concise analytical-numerical form. The structure is reassembled and load is applied incrementally until ultimate strength is attained.In this method, modeling is an obvious operation of dividing the structure into its actual structural units. This eliminates the effort required for the choice of type of element or size of mesh as in the finite element method. The number of structural units and overall degrees of freedom required for the analysis of a structure by this method are less in order than the number of elements and overall degrees of freedom required to analyze the same structure by the FEM. Costs of computer and data preparation may be drastically reduced.Application of the method to metal structures built up of deep I girders, such as bridge girders, ships deep girders and grillage structures is considered. The “Girder Structural Unit” is defined and its behavior under increasing loads is idealized based on existing as well as newly developed theoretical and experimental studies. Conditions for web bucking, ultimate strength and full plastic strength are established and expressions for stiffness during various stages are derived. A deep girder structure may then be treated as an assembly of such “Girder Structural Units”. Results of analysis of example structures are presented. The consumed computer time is found to be very short, as expected. Comparisons with results of experimental studies show good agreement.     

The fatty acid composition of Hibiscus sabdariffa seed oil

Analysis of Hibiscus sabdariffa seed oil from different seed collections (or cultivars), representing different growing areas, showed differences in the fatty acid pattern, especially with respect to linoleic (30.1-37.45%) and epoxyoleic (trace to 5.3%). The results showed different values from those previously reported for the cyclopropenoid fatty acid, found to be malvalic acid (0.4-2.0%), responsible for the positive Halphen response of the oil. It is now also established that the oil contains dihydrosterculic acid (1.0-1.6%) which has been reported previously in other species of the genus Hibiscus. The results of the rest of fatty acids showed ranges for myristic 0.2-0.5%, palmitic 17.4-22.6%, stearic 3.9-5.2% and oleic acid 34.6-39.8%.     

Expected repair cost under doubly stochastic damage processes

There are a number of instances where the problems of non-stationarity, Poisson compounding and double stochasticity arise. In the theory of space-charge limited shot-noise, the number of beats that occur in a given interval of time obey a doubly stochastic process since the Poisson's parameter λ changes randomly due to individual beats. This paper puts forward a doubly stochastic non-stationary compound Poisson process as a model describing damage sustained by military equipment, solar collectors, … etc., due to hailstones. The expected repair cost due to such damage is formulated.     

Hot water defrosting of a horizontal flat plate cooling surfaceDégivrage par eau chaude d'une surface de refroidissement de plaque plane horizontale

Removal of frost from an jupward facing horizontal cooling plate at a subfreezing temperature using a hot water spray is studied experimentally. The variation of the frost layer with time is approximately linear. A simple analytical model predicts the trend of the frost thickness-time change.